<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
    :root {
        --device-width: 770px;
        --device-height: 1336px;
        --ui-width: 640px;
        font-size: 15px;
    }

body {
    background-color: #000;
    margin: 0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    font-family: Helvetica;
    padding: 4rem 0;
}

h2 {
    color: #6e6e73;
    text-align: center;
    font-size: 4.5rem;
    font-weight: 600;
    margin: 6rem 0;
}

h2 p {
  margin: 0;
  color: #fff;
}

#iphone {
  position: relative;
  width: var(--device-width);
  height: var(--device-height);
}

#ui {
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
}
#ui ul {
  list-style: none;
  margin: 0;
  padding: 0;
  --progress: 0;
}

#ui ul li img {
    display: block;
    width: var(--ui-width);
    height: auto;
    margin: 10px auto;
    padding-bottom: 10px;
    border-bottom: 1px solid #222;
    transform: scale(calc(1.8 - (0.8 * var(--progress)))) translateY(calc(-60px * (1 - var(--progress))));
    opacity: var(--progress);
}
    </style>
</head>
<body>
    <h2>
        <p>动画</p>
      </h2>
      <div id="iphone">
        <div id="ui">
          <ul>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_01.jpg" />
            </li>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_02.jpg" />
            </li>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_03.jpg" />
            </li>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_04.jpg" />
            </li>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_05.jpg" />
            </li>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_06.jpg" />
            </li>
            <li>
              <img src="https://assets.codepen.io/2002878/iphone12-5g_show_07.jpg" />
            </li>
          </ul>
        </div>
      </div>
</body>
<script>
    const rows = document.querySelectorAll('#ui ul li')
    const html = document.documentElement

document.addEventListener('scroll', (e) => {
  let scrolled = html.scrollTop / (html.scrollHeight - html.clientHeight)
  
  let total =  1 / rows.length
  
  for (let [index, row] of rows.entries()) {
    let start = total * index
    let end = total * (index + 1)
    
    let progress = (scrolled - start) / (end - start)
    if (progress >= 1) progress = 1
    if (progress <= 0) progress = 0
    
    row.style.setProperty('--progress', progress)
  }
})
</script>
</html>